<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .input-box{
            margin: 10px;
            display: flex;
            align-items: center;
        }
        .input-box input{
            flex: 1;
            height: 40px;
            border: 1px solid #ccc;
            outline: none;
            padding-left: 20px;
            border-radius: 5px;
        }
        .input-box span{
            text-align: center;
            color: lightseagreen;
            width: 60px;
        }
        .list{
            margin: 10px;
        }
        .list .task{
            margin: 20px 0;
            display: flex;
            justify-content: space-between;
            padding: 15px;
            background-color: red;
            color: white;
        }
        .list .task.finished{
            background-color: lightseagreen;
        }
        .empty{
            text-align: center;
            margin: 50px 0;
            color: red;
        }
    </style>
</head>
<body>
    <div id="app">
        <div class="input-box">
            <input type="text" placeholder="输入任务名称" v-model="inputText"> 
            <span @click="add">添加</span>
        </div>
        <div class="list">
            <!-- class 绑定 -->
            <!-- :class=" `task ${item.status?'finished':''}` " -->
            <div :class="{ task: true, finished: item.status }" v-for="(item,index) in tasklist" :key="index">
                <input type="checkbox" @click="changeStatus(item)">
                <div class="name">{{item.name}}</div>
                <span class="btn" @click="deleteTask(item)">删除</span>
            </div>
            <div class="empty" v-show="tasklist.length == 0">任务列表空空如也!</div>
        </div>
    </div>
    <script src="./vue-2.5.21.js"></script>
    <script>
        var v = new Vue({
            el:'#app',
            data:{
                inputText:'',//保存输入框中的值
                tasklist:[
                    /* {id:1, name:'任务名称', status:false } */
                ]
            },
            methods:{
                add(){ //添加任务
                    if( this.inputText ){ //输入框不为空, 才添加任务
                        //构造一个任务对象
                        var obj = { id: this.tasklist.length + 1 ,name:this.inputText, status: false };
                        //将任务对象 添加到任务列表中
                        this.tasklist.push( obj );
                        //清空输入框
                        this.inputText = '';
                    }
                },
                changeStatus(item){ //更改任务状态, item参数就是 当前点击的任务对象
                    item.status = !item.status;
                },
                deleteTask(item){
                    //查找需要删除的元素
                    // this.tasklist.indexOf(item)
                    // this.tasklist.includes(item)
                    // this.tasklist.find(item)
                    var i =this.tasklist.findIndex((it)=>{//返回找到元素的下标
                        return it.id==item.id
                    })
                    //删除任务列表中对应位置的元素
                    if(i!=-1){
                        this.tasklist.splice(i,1)
                    }
                    
                }
            }
        })
    </script>
</body>
</html>